In 2010, the protocol was amended to allow us to treat a subset of returning healthy volunteers with doxycycline to obtain additional biopsies. In 2011, we completed treatment of the additional healthy volunteers. In 2012, we completed the analysis of immunohistochemical staining of the additional biopsies obtained from healthy volunteers treated with doxycycline. In fiscal year 2013, we investigated the serum levels of doxycycline from the healthy volunteers who participated in the study in previous years. Due to insufficient personnel, additional analyses were held. In fiscal year 2017, the protocol was amended to allow additional investigation of skin samples post-UV exposure.